PANAMIC-PACIFIC PELECYPODA 195 



—Prime, 1865, Smith. Misc. Coll., No. 145, p. 30, No. 34, fig. 24.— Sowerby, 



1876, Conch. Icon., vol. 20, Cyrena, pi. 19, fig. 109. 

 Cyrena {Anomala) isocardioides Deshayes, 1855, Proc. Zool. See. London for 185+, p. 



22. Hab. Colombia.— Prime, 1865, op. ciU, p. 25, No. 23 ; Sowerby, 1876, op. cit., 



pi. 18, fig. 103. 

 Polymesoda isocardioides (Deshayes), Maxwell Smith, 1944, Panamic Shells, p. 67. — 



— Hertlein and Strong, 1955, Bull. Amer. Mus. Nat. History, vol. 107, art. 2, pp. 



187, 188, pi. 2, figs. 25, 28. 

 Cyrena cardiformis Sowerby, 1876, op. cit., pi. 8, figs. 27a, 27b Payta, Peru. 



The shell is high, subtrigonal, cordate, inequilateral, the umbones 

 swollen and high, narrowing into the small beaks which do not touch the 

 hinge line and are not closely adjacent to each other. The substance of 

 the shell is thin, the valves strongly inflated, especially along the anterior- 

 umbonal slope; behind this zone, the surface of the disk is impressed with 

 a weak bulge along the posterior-dorsal slope forming a narrow fold; the 

 posterior-dorsal submargin itself is narrowly impressed, the posterior end 

 slightly produced or beaked, especially in the young. The surface is covered 

 with a thin, olive-brown periostracum, often worn off in spots exposing the 

 disk beneath which is white, shaded irregularly with violet, most strongly 

 so on the beak and along the posterior slope. The surface is nearly smooth 

 across the middle zone with irregular concentric growth lines showing on 

 the sides. Cavity of shell deep, the hinge weak, the lateral teeth elongated. 



Length 49 mm., height 46.5 mm., diameter 40.4 mm. Tumaco, Colombia. 



This species is recognized by its high, trigonal shape, markedly in- 

 flated, thin, cordate valves and its more or less pointed or beaked posterior 

 end. Young shells are thin and the posterior beak is pronounced. 



Range — Nicaragua to northern Peru. Nicaragua: Corinto. Colombia: 

 Isla del Gallo; Tumaco. Ecuador: Santa Elena. Peru: Tumbez; Boca Pan. 



Polj-iuesoda (Egeta) inflata (Pmiippi) Plate 27, figures 3, 3a, 5 



Cyrena inflata Philippi, 1851, Zeit. f. Malak., p. 71.— Prime, 1865, Smith. Misc. Coll. 



No. 145, p. 26, No. 26. 

 Cyrena maritima C. B. Adams, 1852, Ann. Lyceum Nat. Hist. New York, vol. 5, pp. 



499, 545. — Sowerby, 1878, Conch. Icon., vol. 20, Cyrena, pi. 8, fig. 30. — Turner, 



1956, Occas. Papers on Mollusks, Comp. Zool., vol. 2, No. 20, pp. 62, 63, pi. 



20, figs. 5, 6. 

 Cyrena inflata Deshayes, 1854, Proc. Zool. Soc. London, p. 23 preoccuppied by C. 



inflata Philippi, 1851 Panama. 

 Cyrena panamensis Prime, 1860, Proc. Acad. Nat. Sci. Philadelphia, vol. 12, p. 2S3 new 



name for C. inflata Deshayes preoccuppied. — Prime, 1865, op. cit. No. 145, 



p. 24, No. 20. — Sowerby, 1878, Conch. Icon., vol. 20, Cyrena, pi. 8, fig. 29. 

 Cyrena isocardioides (Deshayes), Dall, 1909, Proc. U. S. Nat. Mus., vol. 37, No. 1704, 



p. 159, pi. 26, fig. 4. (Not C. isocardioides Deshayes, 1855.) 

 Polymesoda joseana Morrison, 1946, Smith. Misc. Coll., vol. 106, No. 6, p. 44, pi. 1, 



figs. 12-14. 

 Cyrena cordiformis Recluz, 1835, Jour, de Conchyl., vol. 4, p. 251, pi. 7, fig. 9 (no 



locality cited). Not C. cordiformis Deshayes, 1824. 

 Cyrena recluzii Prime, 1865, op. cit., vol. 7, No. 145, p. 24, fig. 19. Hab. PCentral 



America. 

 Polymesoda recluzii (Prime), Hertlein and Strong, 1947, Zoologica, vol. 31, pt. 4, pp. 



148, 149. 

 Cyrena peruviana Deshayes, 1854, Cat. Conch. Bivalve Shells, Brit. Mus., pt. 2, p. 



259. Hab. Tumbez in littori Peruviana (coll. Cuming). 



The shell is generally large, thin, strongly inflated, subrectangular in 

 shape, the umbones swollen, wide, ending in small, prosogyrate beaks touch- 



